1988-04-29_PERMIT FILE - C1981008A (45)

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structures owned by Peabody. Ground Vibration. Peabody utilizes the scale-distance equation W = (D/60)2 to determine the allowable charge weight of explosives to be detonated in any 8-millisecond period. Thus, seismic monitoring is not conducted. The equation will be applied to protect the facilities identified in Rule 4.08.4(10). Computation of the formula will be recorded on the blasting record form (Attachment 14-3) for each blast. Peabody may perform seismographic surveys for the purpose of acquiring data. If a request for the use of a modified equation to determine the weight of explosives per delay is submitted to the CMLRD, this data will be included into the request as appropriate. Reports of seismographic surveys will be filed at the mine office, if performed. Peabody will utilize the formula W = (D/60)2 at the Nucla Mine until the CMLRD approves a request for a modified equation. However, seismograph instruments will be utilized at the Nucla East area to monitor compliance with the vibration limitations in lieu of utilizing the scaled distance equation. This is further discussed in the blast design section of this tab. Fly Rock. Stemming is loaded into blastholes prior to detonation to substantially reduce the occurrence of fly rock. The depth of stemming will range from approximately 67 to 100 percent of the burden distance. Fly rock which may result from blasting operations shall not be cast from the blasting site more than one-half the distance to the nearest dwelling or other occupied structure, and in no case beyond the area of control or beyond the line of property owned or leased by Peabody. Blasting Schedule All blasting will be conducted between sunrise and sunset at times and at locations defined in the published blasting schedule. Unscheduled blasts would be conducted only where public or operator health and safety so require and for emergency blasting actions described in the blasting schedule. The blasting schedule will identify as accurately as possible the location of the blasting site and the time periods when blasting will occur. The blasting schedule will contain at a minimum: 14-4 Revised 04/11/88